1. Scope of the Invention
The present invention relates to a calender for, e.g., paper and similar web material. The calender includes a roll stack having at least four rolls, bearing blocks, and a frame for retaining the bearing blocks. The bearing blocks are either affixed to the frame or mounted to the frame for vertical movement. The calender also includes a load device that acts on at least one of the bearing blocks of an upper roll, i.e., from above, and the bearing blocks of the lower roll, i.e., from below.
2. Discussion of Background Information
Multiple roll calenders of the type generally described above are known, e.g., German Patent No. DE 28 23 738 C2. The roll stack includes a number of rolls, e.g., 14. The roll stack is brought into an operating position via a lower load device and loaded via an upper load device with forces that, together with the weight of the rolls, exert a compressive strain in the roll nips. The lower load device supports itself on a base of the frame and the upper load device is supported on the top of the frame.
Recently, calenders having a number of rolls reduced to between five and eight rolls, see, e.g., German Patent Application No. DE-U-295 04 034, obtain a same glazing result as the prior art. However, in these devices, the roll temperatures are raised and the roll nips are subject to a heavier load, e.g., with a middle compressive strain in the lowest work nip of greater than 42 N/mm.sup.2. As a result of these greater load forces, the calenders require more strongly dimensioned frames.
In two-roll-calenders, as discussed in, e.g., German Patent Application No. DE 42 31 472 A1, it is known to connect the bearing blocks of both rolls by incorporating the load device through tensile rods. In this manner, the frame may be dispensed with.